1. Technical Field
The present invention relates to a liquid-jet head, a method of manufacturing the liquid-jet head, and a liquid-jet apparatus. Specifically, the present invention relates to an inkjet recording head with the following configuration, a method of manufacturing the inkjet recording head, and an inkjet recording apparatus. In accordance with the configuration, parts respectively of pressure generating chambers communicating with corresponding nozzle orifices from which to eject ink droplets are constructed of a vibration plate, and piezoelectric elements are on the surface of this vibration plate. Accordingly, the ink droplets are ejected in response to displacement of the piezoelectric elements.
2. Related Art
An inkjet recording head with the following configuration can be enumerated as the liquid-jet head which ejects liquid droplets. In accordance with this configuration, for example, parts respectively of pressure generating chambers communicating with corresponding nozzle orifices are constructed of a vibration plate. This vibration plate is distorted by piezoelectric elements, and thus ink in each of the pressure generating chambers is pressurized. Thereby, ink droplets are ejected from the nozzle orifices. In addition, the following two types of inkjet recording heads have been put into practical use. A first type of inkjet recording head uses piezoelectric actuators of vertical vibration mode which extend and contract in the axial direction of the piezoelectric elements. A second type of inkjet recording head uses piezoelectric actuators of deflection vibration mode.
In addition, an inkjet recording head with the following configuration has been known as the inkjet recording head using the piezoelectric actuators of deflection vibration mode. In accordance with this configuration, for example, an even layer made of a piezoelectric material is formed on the entire surface of the vibration plate by use of a film-forming technique. Then, this layer made of the piezoelectric material is cut into shapes corresponding to the pressure generating chambers by the lithography method. Thereby, the piezoelectric elements are formed respectively for the pressure generating chambers in order that the piezoelectric elements can be independent from one another. Piezoelectric elements of this type can be arranged in a relatively high density.
Piezoelectric elements formed by use of the film-forming technique in this manner have an advantage that the piezoelectric elements can be arranged in a high density, and that print quality can be accordingly improved. However, the piezoelectric elements have a disadvantage, for example, that the piezoelectric elements are prone to be broken due to the external environment including dampness and the like.
There is an inkjet recording head with the following configuration for the purpose of making up for this unsatisfactory condition. In accordance with this configuration, for example, a sealing plate (a reservoir-forming plate) having a piezoelectric element holding portion is joined to a passage-forming substrate, and thus the piezoelectric elements are sealed up within this piezoelectric element holding portion (see JP-A-2003-136734, for example). Pressure generating chambers are formed in the passage-forming substrate. Even if, however, the piezoelectric elements are sealed up with the piezoelectric element holding portion, there is still a problem that the piezoelectric elements are broken due to dampness inside the piezoelectric element holding portion. This is because the dampness level inside the piezoelectric element holding portion gradually rises due to moisture coming into the piezoelectric element holding portion through an adhesion portion where the sealing plate and the passage-forming substrate are joined to each other.
In addition, there is an inkjet recording head in which, for example, the piezoelectric elements are covered with an insulation film made of an inorganic insulation material such as aluminum oxide (see International Publication WO-2005-0828207, for example). Indeed, such a configuration makes it possible to prevent the piezoelectric elements from being broken due to the external environment including dampness and the like. However, such a configuration has a problem, for example, that the configuration has a low resistance to chemical liquids including a developing solution. To put it another way, when the insulation film is soaked in a chemical liquid such as a developing solution after the insulation film is formed, the thickness of the insulation film becomes thinner. For this reason, the thickness with which the insulation film is formed has to be thicker than a desired thickness. Accordingly, this brings about a problem that the material is consumed wastefully, and that the piezoelectric elements are manufactured inefficiently. Moreover, while the film thickness of the insulation film is decreasing, the film thickness becomes uneven. As a result, it is likely that distortion of each of the piezoelectric elements may become uneven as well.
It should be noted that these types of problems are present not only in inkjet recording heads which eject ink droplets, but also in liquid-jet heads which eject liquid droplets other than the ink droplets.